The present invention relates to optical spectroscopy, and more particularly, to an active spectrometer that performs spectroscopic analysis over a broad wavelength range with high resolution.
A spectrometer is an optical instrument that focuses light entering the spectrometer through a slit (entrance slit). The light is focused on a focal plane, and a location on the focal plane varies as a function of the frequency (or wavelength) of the light. A single frequency of light entering the slit will produce a single line on the focal plane, while multiple frequencies of light will produce multiple corresponding lines on the focal plane. Typically some variation in wavelength is present, and this in combination with instrumental imperfections, produces narrow wavelength bands rather than true lines (i.e., single wavelengths of light).
A typical high resolution spectrometer resolves incoming light into a large number of finely resolved wavelength bands. These wavelength bands are detected by a detector (or detector array) placed along the focal plane of the spectrometer. The spectrometer's spectral coverage is generally determined by the size of the spectrometer's detector (or detector array), and for a given detector size (detector array size), the spectrometer's resolution is generally determined by detector element, or pixel, width.
Detectors having large arrays of densely packed elements or pixels (i.e., large high-resolution detectors) necessarily generate large volumes of data and require significant computational resources to process this volume of data.
Spectroscopic detection of a particular chemical substance (or trace element) in a mixture of substances often involves discerning several relatively faint spectral lines, characteristic of the particular chemical substance, in the presence of nearby higher intensity spectral lines associated with the other substances in the mixture. Further, the particular substance's characteristic spectra may be distributed over a very large spectral range.
For example, the Balmer series spectra has significant spectral lines over the range of roughly 380 nanometers to exactly 656 nanometers. To detect the complete Balmer series would require sampling of many narrow wavelength bands over a broad spectral range resulting in the generation of a relatively large amount of data. Accordingly, intensive computational resources are often required to process and store the data generally associated with performing high-resolution chemical substance detection over a broad spectral range.
Accordingly, there exists a need for a high-resolution, broad-band spectrometer that uses relatively low-cost detectors and avoids the use of relatively large computational resources.
The present invention satisfies these and other needs.